This invention relates to a method of producing a frozen blanched green agricultural product and an apparatus therefor.
In order to commercially distribute green agricultural products (for example, kidney beans in pods, soybeans in pods, sweet pease, broad beans), green agricultural products of good qualities are blanched either in steam or in water in order to inactivate enzymes, then frozen and forwarded to the market.
Many have attempted to to develop a method of producing a frozen green agricultural product which uses a blanching step, to prevent softness, freshness and deliciousness taste from deteriorating until actually eating these products. However, no technique has been established hitherto for maintaining the taste of a product in season throughout the frozen-storage period.
In the case of broad beans, for example, processing conditions should be delicately changed depending on the extent of the maturity, variety freshness of the beans and the processing scale, which makes it difficult to produce uniforms and tasty products.
Furthermore, a troublesome cooking operation, i.e. heating or further blanching is required before taking these products which are produced in conventional method.
The present invention has been accomplished under these circumstances, and it is an object of the present invention to provide a method of producing a frozen food which maintains the softness, freshness and taste of a green agricultural product and an apparatus therefor.
More particularly, it is an object of the present invention to provide a method of producing a frozen green agricultural product whereby a green agricultural product can be blanched without deteriorating its softness, freshness or taste and then the blanched product is frozen as such to produce a frozen food maintaining its softness, freshness and taste which can be eaten as such without heating or further blanching after thawing.
It is another object of the present invention to provide a package for maintaining the bright green color of agricultural products.
It is another object of the present invention to provide an apparatus for blanching a green agricultural product whereby a green agricultural product can be blanched at a high efficiency to thereby give a tasty product in a bright green color.
More particularly, another object of the present invention is to provide an apparatus for blanching a green agricultural product whereby the time and temperature for a hydrothermal treatment and steam-cooking can be controlled to establish the optimum treating conditions which should be changed depending on the type, extent of maturity and freshness of the green agricultural product.
The green agricultural products to be processed in accordance with the present invention include beans such as green peas in pods, kidney beans in pods, soybeans in pods, broad beans, green pease and solid vegetables in a green color such as green asparagus. Now, the present invention will be illustrated regarding soybeans in pods by way of example. The degree of blanching soybeans in pods is determined depending on the sum of the blanching temperature and time. As the blanching is effected at a higher temperature for a longer period of time, the soybeans in pods become yellowish and the hue is deteriorated. Even though the blanching temperature is low, the hue is deteriorated with a prolonged blanching time. Therefore, it is necessary to minimize the blanching time while taking the hardness and texture of the beans into consideration.
To achieve the above mentioned and other objects, the present invention provides a method of producing a frozen green agricultural product including a step of blanching the green agricultural product. The blanching step includes steps of changing the color and brightness, and swelling the green agricultural product, the swelling step is to swell and soften the product. The present invention thus provides a frozen food of a green agricultural product produced by the above mentioned method wherein, a combination of a coloring step of treating a green agricultural product in hot water within a short period of time and a swelling step of steam-cooking (at 95-100xc2x0 C.) is employed. These steps make it possible to produce a blanched green agricultural product having a soft texture without deteriorating the freshness or taste thereof. The processed product thus obtained can be frozen as is and thus the softness, freshness and taste can be maintained. After thawing, it can be eaten as is without heating.
To achieve another object, the present invention provides a package of a frozen blanched soybean in pod packaged by a colored transparent package material wherein the color is green, blue or red.
To achieve another object, an apparatus for blanching a green agricultural product comprising a cylinder including a coloring zone and a swelling zone, a steam inlet for supplying steam into the cylinder, and a transporting mechanism for transporting a green agricultural product within the cylinder.